The present invention relates to a method for detecting and measuring trace amounts of various aerosols in a gaseous environment. As used herein the term aerosol relates to the organic and inorganic pollutant materials, usually solids, that are suspended within the earth's atmosphere. In one aspect, the invention relates to a method for detecting and measuring specific aerosols which could aid in the development of a detector for rapid identification of effluent sources. Also, the invention could serve as an experimental tool for study of heterogeneous chemistry and study of formation of toxic, electronically excited species in airborne particles.
There are many known methods of determining the presence of trace impurities or various pollutants in a gas such as the earth's atmosphere. However, several of these methods require the use of devices that are cumbersome, expensive, or both, and there is a need for a simple and inexpensive reliable technique. This need is particularly acute in spacecraft and other installations where weight and bulkiness are of primary importance. Previous methods for aerosol analysis include gas and liquid chromatography, mass spectroscopy, electron microscopy, x-ray fluorescence, and wet chemical analysis. Methods for measuring aerosol concentration include high volume samples, turbidity meters, and other particle counting instruments, none of which measure chemical composition.
A previous process for measuring trace amounts of ozone, nitrogen oxide and carbon monoxide, and similar in some respects to the present invention is disclosed in U.S. Pat. No. 3,977,831. This patented process involved pollution detection wherein the pollutant reacted with a solid organic material that inherently chemiluminescensed when heated and the total integrated light intensity, measured during the heated cycle being a measure of pollutant exposure. In the present invention an aerosol is reacted with an ozone environment and the reactant product exposed to a fluorescer. The sample is then subjected to a heating profile, linearly programmed at 30.degree. C. per minute to a temperature of 200.degree. C. The peak intensity of the fluorescer thermoluminescence during this heating serves as an indication of the aerosol tested.
Accordingly, it is an object of the present invention to provide a simple and reliable technique for detecting and measuring trace amounts of various aerosols in a gas. It is further an object to provide such a process which utilizes organic materials that undergo chemical changes and serve as transfer agents or indicators of selected aerosol/ozone reactions and thereafter undergo chemiluminescence when heated.
Another object of the present invention is to provide a process of measuring peak intensity of a thermoluminescent reaction as a function of a specific aerosol.